Biology Question

Question

What evolutionary factors are responsible for the current decline in heritable phenotypic variation? What would happen to a population if there was no more introduction of fresh allelic variation? What would occur if mutation were totally eradicated? Why would this be detrimental to the long-term success of a population?

Answer 1

There are a number of evolutionary factors that are responsible for the current decline in heritable phenotypic variation:

1. Genetic drift: Genetic drift is the random change in allele frequencies in a population over time. It can occur due to small population size, founder effects, and bottlenecks. Genetic drift can lead to the loss of rare alleles and a decrease in overall genetic diversity.
2. Natural selection: Natural selection is the process by which individuals with traits that are better suited to their environment are more likely to survive and reproduce. Over time, this can lead to a decrease in genetic variation, as the population becomes more and more uniform.
3. Inbreeding: Inbreeding is the mating of closely related individuals. This can lead to an increase in the frequency of homozygous recessive alleles, which can cause genetic disorders. Inbreeding can also reduce genetic diversity, as it prevents the introduction of new alleles into the population.
4. Habitat loss and fragmentation: Habitat loss and fragmentation can lead to isolated populations. This can reduce gene flow between populations and increase the risk of genetic drift and inbreeding.
5. Climate change: Climate change can cause rapid changes in the environment, which can put populations under stress. This can lead to natural selection for different traits, which can reduce genetic diversity.

If there was no more introduction of fresh allelic variation, the population would become more and more inbred. This would increase the risk of genetic disorders and reduce the population's ability to adapt to environmental changes.

If mutation were totally eradicated, the population would become fixed for the alleles that are already present. This would mean that the population would have no genetic variation, and would therefore be unable to adapt to environmental changes.

Both of these scenarios would be detrimental to the long-term success of a population. A population with low genetic diversity is more likely to go extinct in response to environmental changes.

In addition to the evolutionary factors listed above, there are a number of human-caused factors that can also contribute to the decline in heritable phenotypic variation. These include:

1. Overfishing: Overfishing can lead to the decline of populations of fish and other marine animals. This can reduce genetic diversity, as it prevents the introduction of new alleles into the population.
2. Habitat destruction: Habitat destruction can lead to the fragmentation of populations and the loss of genetic diversity.
3. Pollution: Pollution can cause genetic mutations and reduce the fitness of individuals. This can lead to a decrease in genetic diversity and an increase in the risk of extinction.

It is important to protect genetic diversity in order to ensure the long-term survival of populations. This can be done by protecting habitats, reducing pollution, and managing populations sustainably.